1. Field of the Invention
This invention relates to the field of plant breeding. In particular, it relates to methods and reagents for quantitatively determining the genetic contribution of each parent in the progeny of a genetic cross between parental plants of different species, subspecies, or varieties. The invention also provides methods for selecting progeny plants having a desired trait or combination of traits that have inherited a minimum amount of DNA from the trait donor species, subspecies or variety. Reagents comprising nucleic acid probes specific for plant species, subspecies and varieties are also provided by the invention.
2. Description of the Prior Art
Genetic uniformity leads to susceptibility of crop plants, horticultural plants and other useful and economically important plants to many pests and pathogens resulting in widespread epidemics. This is of great concern to the plant breeder. To introduce genetic diversity into these plants, it is often desirable to introduce traits into existing varieties through outcrosses to the exotic or wild species of the same genus. The major drawback of crosses between plants of different species is that large numbers of backcrosses to the existing varieties are necessary to eliminate deleterious and/or undesirable traits present in the progeny that are derived from the exotic or wild species.
Traditional methods of plant breeding following outcrossing involves selection of progeny plants based on phenotypic traits. Although traditional methods are useful in selecting individual characters (e.g., disease resistance), selection of those hydbrid progeny most genetically similar to either of the parental species is inefficient using these methods.
Because those hybrid progeny which have inherited the least amount of DNA from one parent will most genetically resemble the other parent, methods capable of differentiating the relative contribution of each parent to the genomic DNA of the hybrid would be useful in selecting the appropriate hybrids for further propagation by backcross to the desired parental species.
Nucleic acid probes specific for particular species, subspecies or varieties of plants are capable of differentiating between the relative genetic contribution of each parent to the genomic DNA of a progeny plant in a genetic cross between plants of different species, subspecies or varieties. The prior art describes a variety of nucleic acid probes that bind to plant DNA.
Rayburn and Gill, 1985, J. Hered. 76: 78-81 describe the use of biotin-labeled probes to map specific DNA sequences on wheat chromosomes.
Lander and Botstein, 1989, Genetics 121: 185-199 describe the mapping of Mendelian factors using restriction fragment length polymorphisms.
Zhao et al., 1989, Theor. Appl. Genet. 78: 201-209 describe genome-specific repetitive sequences as useful markers for studying plant genome evolution and species divergence.
Zischler et al., 1989, Hum. Genet. 82: 227-233 describe digoxigenated oligonucleotide probes specific for simple repeats and applications of such probes to fingerprinting and in situ hybridization studies.
Hillel et al., 1990, Genetics 124: 783-789 describe the application of DNA fingerprint techniques to introgression plant breeding programs.
Itoh et al., 1991, Theor. Appl. Genet. 81: 356-362 describe studies involving species-specific DNA probes.